1. Cleaning Requirements for Photovoltaic Modules

1.1 When to Clean

Regular cleaning is essential to maintain optimal power generation efficiency. According to China's technical standard T/CAPE 11005-2023, cleaning decisions should be based on:

Power loss assessment: When soiling-induced power loss exceeds 5% of rated output

Visual inspection: Noticeable accumulation of dust, bird droppings, leaves, or industrial residue

Seasonal factors: Pollen seasons, dry periods with minimal rainfall, or post-construction debris

1.2 Cleaning Methods

Water Cleaning (Standard Method)

Use demineralized or low-mineral water to prevent spotting and scaling

Water pressure should not exceed 5 MPa to avoid module glass damage

Cleaning temperature range: 5°C to 35°C (avoid extreme thermal shock)

Mechanical Cleaning

Soft roller brushes or microfiber pads are recommended

Automated cleaning robots suitable for utility-scale ground-mounted systems

Avoid abrasive tools that may cause micro-scratches on anti-reflective coating

1.3 Safety Considerations

All cleaning personnel must be properly trained for working at height

For rooftop systems, fall protection equipment and safety harnesses are mandatory

Never clean modules during operation if electrical hazards exist; systems should be shut down or cleaned at night/early morning

Avoid stepping directly on solar modules - use designated walkways or mounting rails

1.4 Functional Principle

Dust and soiling reduce light transmission to the photovoltaic cells through two mechanisms:

Absorption: Particles absorb incident sunlight before reaching the glass surface

Scattering: Particulate matter scatters light away from the module active area

This soiling effect can reduce annual energy yield by 5-25% depending on the installation environment (desert, agricultural, or industrial areas).

2. Lightning Protection and Grounding Systems

2.1 Why Lightning Protection Matters

Photovoltaic power plants, by virtue of their outdoor exposure and large surface area, are particularly vulnerable to lightning strikes . A direct or nearby strike can induce voltage surges reaching tens of thousands of volts, leading to:

Inverter and charge controller damage

Fire hazards from arcing

Complete system shutdown and costly repairs

Personnel safety risks during maintenance

2.2 Key Components

Air Terminals (Lightning Rods)

Installed at elevated points above the array

Typically made of round steel rods (12-16mm diameter) with hot-dip galvanized coating

Function: Capture the lightning discharge and direct it safely downward

Down Conductors

Transport lightning current from air terminals to ground

Preferred materials: Hot-dip galvanized round steel or flat steel (minimum 40mm × 4mm cross-section)

Spacing between down conductors should follow local electrical codes

Grounding Electrodes

Dissipate lightning energy into the earth

Common specifications:

Steel pipe: Minimum 50mm diameter, 3.5mm wall thickness

Angle steel: 50mm × 50mm × 5mm

Horizontal grounding conductors buried at least 0.5m depth (below frost line)

Vertical electrodes driven 2.5m or deeper

Equipotential Bonding

Ensures all metal components maintain the same voltage during a surge event

Module frames and mounting rails must be bonded together using 4mm² yellow-green conductors

Prevents side-flashing (arc discharge) between components at different potentials

2.3 Best Practices for PV Plants

Separation of Grounding Systems

Equipment grounding and lightning protection grounding should be kept separate

Maintain minimum 10m distance between different grounding conductor paths

Critical: Never connect inverter PE (protective earth) directly to lightning down conductors

Surge Protection Devices (SPDs)

Install Type 1 SPDs at the DC input of inverters (Iimp ≥ 5kA, 10/350μs waveform)

Install Type 2 SPDs at AC grid connection points

Always install a circuit breaker or fuse ahead of SPDs to prevent fire if the SPD fails

Shielding

Use metallic conduit or cable trays with grounding continuity

Enclose sensitive electronics in grounded metallic enclosures (LPZ protection zones)

2.4 Application Scenarios

3. Wind Resistance Requirements

3.1 Structural Principles

Wind loads on PV modules create both uplift (lifting force) and downward pressure. The magnitude depends on:

Array tilt angle: Higher tilt angles increase wind exposure

Module row spacing: Wind acceleration between rows can amplify forces

Installation height: Elevated structures experience higher wind speeds

Terrain category: Open fields have higher design wind speeds than urban areas

Modern mounting systems are designed using spatial cable–truss architecture, where tensioned pre-stress elements distribute loads more effectively than conventional rigid frames . Under wind loading, the structure flexes slightly, converting kinetic wind energy into structural tension without permanent deformation.

3.2 Testing and Standards

ASCE 7-22 (USA)

Updated every six years by the American Society of Civil Engineers

Introduces new wind, snow, seismic, and tornado load criteria

Design wind speeds are based on 700-year return period events

CSA C451 (Canada – Draft 2026)

Laboratory test method for dynamic wind load resistance

Applies to arrays with tilt angle ≤35° from roof surface

Uses hydraulic or pneumatic actuators to simulate cyclic wind loading

Wind Tunnel Testing

For large-scale or unconventional designs, physical wind tunnel validation is recommended

Recent research on double-row flexible PV supports shows wind direction and inclination angle significantly impact pressure distribution

Maximum wind pressure coefficients can reach -1.572 (uplift) at corner zones

3.3 Design Recommendations

3.4 Case Study: Typhoon Resilience

A 70 MW fishery complementary PV project in Hainan successfully withstood Super Typhoon Yagi (Category 17 equivalent) using flexible mounting technology. Post-storm inspection by TÜV confirmed:

No module deformation or glass breakage

No micro-cracks detected

No structural compromise

3.5 Application Scenarios by Wind Zone

4. Snow Load Requirements

4.1 Functional Challenge

Snow accumulation on PV modules creates three distinct risks:

Mechanical overload: Excessive weight can exceed the module's mechanical load rating (typically 5400Pa or ~550 kg/m²)

Non-uniform distribution: Drifting and sliding snow creates uneven loading that concentrates stress

Power loss: Snow cover completely blocks light transmission, reducing output to near zero

4.2 Standards and Testing

GB/T 46988-2025 / IEC 62938:2020

China's upcoming national standard (effective July 1, 2026)

Equivalent to international IEC standard

Defines non-uniform snow load testing methodology

Simulates realistic snow drift patterns rather than assuming uniform blanket coverage

ASCE 7-22 Snow Updates

Net increase in design snow loads: 10-20% across many US regions

Lower load factors but higher thermal factors for snow melting/refreezing cycles

May require closer rail spacing or additional purlins in high-snow areas

4.3 Design Strategies for Snow-Prone Regions

Active Removal Measures

Roof-mounted systems with tilt angles ≥30° promote natural snow sliding

Heating elements embedded in modules (available as premium option)

Manual removal using foam snow rakes (never metal tools)

Structural Measures

Increased rail density (reduced spacing between support points)

Enhanced end clamps to prevent modules from sliding downward

Stop blocks or snow guards at array lower edge

4.4 Application Scenarios

Summary Table: Environmental Requirements at a Glance

References

Solar Energy UK. Rooftop O&M Guidelines 3.0 (2025)

Growatt. The Ultimate Guide to Lightning Protection and Grounding for C&I PV Power Plants (2025)

CSA Group. Draft Standard C451: Dynamic Wind Load Resistance of Photovoltaic Roof Assembly (2026)

Unirac. Solar Mounting Systems Built to ASCE 7-22 Standards (2026)

DAS Solar. Flexible Mounting Systems for Complex Terrain (2025)

China Standard T/CAPE 11005-2023. Technical Specifications for PV Module Cleaning

SOLARZOOM. Lightning Protection and Grounding for Grid-Connected PV Systems

Journal of Wind Engineering. Double-row PV Panel Aerodynamic Characteristics (2024)

China Standard GB/T 46988-2025 / IEC 62938:2020. Non-uniform Snow Load Testing

Longsun Green
Longsun Green is a professional manufacturer of solar mounting structures for residential, commercial, and utility-scale applications. Our products are engineered to meet international wind, snow, and seismic standards.
📧 amber@longsungreen.com | 🌐 www.longsungreen.com